4-addition and [3 + 2] cycloaddition reactions using chiral calcium species prepared from calcium isopropoxide and chiral bisoxazoline ligands have been developed. Glycine Schiff bases reacted with acrylic esters to afford 1,4-addition products, glutamic acid derivatives, in high yields with high enantioselectivities. During the investigation of the 1,4-addition reactions, we unexpectedly found that a [3
Etude de la reaction chlorocarbene-acetals de cetenes
作者:N. Slougui、G. Rousseau
DOI:10.1016/s0040-4020(01)96366-5
日期:1985.1
The reaction of chloro, chloromethyl and chlorophenyl carbenoids with ketene alkylsilylacetals has been studied. Excellent yields of cyclopropanation were observed and the unstable chlorocyclopropanone acetals formed were thermallyrearranged in high yield into α-substituted α,β-ethylenic esters. This new method for the synthesis of unsaturated esters appeared complementary of the known-ones.
Synthetic studies on ethyl α,β-unsaturated β-nitrocarboxylates (IV) through two routes are described. Ethyl α-hydroxy-β-nitrocarboxylates (II) obtained by the reactions of ethyl α,β-unsaturated carboxylates with fuming nitric acid or by those of nitroparafins with ethyl glyoxylate, were treated with acetic anhydride to afford ethyl α,-acetoxy-β-nitrocarboxylates (III), which were subsequently converted
Synergistic Relay Reactions To Achieve Redox‐Neutral α‐Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
作者:Chen‐Chen Li、Jian Kan、Zihang Qiu、Jianbin Li、Leiyang Lv、Chao‐Jun Li
DOI:10.1002/anie.201915218
日期:2020.3.9
the first Grignard-type nucleophilic addition using olefinicalcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and
Regioselective Synthesis of β-Aryl- and β-Amino-Substituted Aliphatic Esters by Rhodium-Catalyzed Tandem Double-Bond Migration/Conjugate Addition
作者:Dominik M. Ohlmann、Lukas J. Gooßen、Markus Dierker
DOI:10.1002/chem.201100654
日期:2011.8.16
unsaturated esters. Once the double‐bond is in conjugation with the carboxylate group, they also catalyze the Michael addition of carbon and nitrogen nucleophiles. In the presence of these catalysts, unsaturated carboxylates enter a dynamic equilibrium of positional and geometrical double‐bond isomers. The conjugated species are continuously removed through 1,4‐additions with formation of β‐amino esters or